Delta released a statement saying the system issues began with a power outage in Atlanta around 2:30 a.m.

The full statement is below.

A power outage in Atlanta, which began at approximately 2:30 a.m. ET, has impacted Delta computer systems and operations worldwide, resulting in flight delays. Large-scale cancellations are expected today. All flights enroute are operating normally. We are aware that flight status systems, including airport screens, are incorrectly showing flights on time. We apologize to customers who are affected by this issue, and our teams are working to resolve the problem as quickly as possible. Updates will be available on news.delta.com.

Delta suggests checking your flight status before you head to the airport while these issues are being resolved.